1. Field of the Invention
The invention relates to nonvolatile memory integrated circuits generally, and more particularly to error detection and error correction of data that are read from nonvolatile memory.
2. Description of Related Art
The purpose of nonvolatile memory is to store data reliably, such that power loss does not affect the integrity of the stored data. To allow for unforeseen charge gain or charge loss that might affect a threshold voltage of a nonvolatile memory cell, a margin separates threshold voltage ranges that represent different logical levels. However, despite this margin, errors nevertheless occur, such that a data bit programmed as a high logical level will be read as a low logical level, or vice versa.
Although error correction and error detection algorithms will address some of these errors, error correction and error detection algorithms are only designed to handle a limited number of incorrect bits. After this limit is exceeded, error correction and error detection algorithms are insufficient. Moreover, error detection will detect, but not correct, such errors.
Therefore, a need exists for an improvement that makes nonvolatile memory integrated circuits more robust in the face of errors.